Armesto et al LUP 2010.pdf - IEB

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J.J. Armesto et al. / Land Use Policy 27 (2010) 148–160 155Fig. 8. Two areas illustrating recent trends in land cover change in south-central Chile. Above, the Province of Quillota, which is one of the targets of expanding new crops.Below, the Province of Arauco, located at the heart of the plantation forestry industry. The cover maps on the right hand show the main land cover types in each region. Ineach of these two Provinces, estimated changes in cover for the past 15 years show expansion of crops and monocultures of fiber-producing exotic trees (see text).most international trade standards. However, expanding woodlandcover in the Chilean central provinces is primarily the result of plantationsof fiber-producing trees. We estimated that in the provinceof Arauco (37 ◦ S; Fig. 8), at the heart of the plantation industry,where sparse cover of native forest remains, native forest cover furtherdeclined, while the area of monocultures increased from 43to 53% during the period from 1983 to 1998 (Mora et al., in preparation).In the vicinity of Puerto Montt and Chiloé Island (Fig. 1A),presently the southern frontier of plantation forestry, wetlands andmoorlands have become sensible targets for the next generationof eucalypt plantations, still taking advantage of public subsidies.Degraded and burned stands of the valuable conifer Pilgerodendronuviferum and relict lowland populations of Nothofagus antarctica,onpoorly drained soils (Armesto et al., 1995) are also being eradicatedby expanding Eucalypt monocultures, thus reducing the chances forrecovery or restoration. These plantations are expected to accruelarge externalities because of disruption of hydrologic cycles andwater supplies to rural areas, which are regulated by the waterstorage capacity of Sphagnum moorlands (F. Díaz, personal communication),where most plantations are now located.In central Chile, in the Mediterranean sclerophilous forestregion, new crops have become the main drivers of land coverchange in the past 30 years. In the province of Quillota (33 ◦ S;Fig. 8), one of the target areas for the expanding wine and avocado(Persea americana) industries, the analysis of aerial photos showsan increase in the cultivated area from 32 to 42% in the period from1983 to 2001 (Mora et al., in preparation). In the past 20 years,avocado plantations have tripled and the area of vineyards hasnearly doubled at the expense of native vegetation on steep hillsides(Figs. 9 and 10). Such trends are coincident in time with the signatureof Chilean free-trade agreements with the US and the EuropeanUnion. New technologies for site preparation and planting on steephillsides have severely depressed scrublands cover from previouslyinaccessible sites. Because
156 J.J. Armesto et al. / Land Use Policy 27 (2010) 148–160Table 2A framework for climatic and human-driven land cover changes during the last 16,000 years in southern South America, with parallel changes in other temperate regionsof the world. Based on literature cited in the text. Knowledge of climatic and socio-economic drivers of human behavior and policy decisions in response to environmentalchange can be actually or potentially applicable to understand, anticipate, and prevent future land use trends.Chronology for southernSouth AmericaMain land cover transitionMain climatic orsocio-economic driverPolicy decisions and/orhuman behavioral patternsMain transitions and driversin other regions of the worldPostglacial (16,000-12,000)and early Holocene(12,000–6000 BP)Agricultural expansion (5000BP to 1500 AD)Colonial period (1500 to1800s)Preindustrial–industrial(mid-19th century tomid-20th century)Industrial–postindustrial(mid-20th century topresent)Rapid forest expansion fromglacial refugia.Decline of forests and localincrease of open areas.Large-scale deforestation,timber exports to colonies,maximum expansion of openland.Extreme deforestation, andvast soil erosion.Fiber farms expand,homogenization oflandscapes, limited forestrecovery.Climate warming, hunting ofmegafauna, peak in fireincidence.Farming and land clearing byaboriginal people in riverbasins.Food demands from NorthAmerica and Europe, wheatcrops. Miners’ rush, fuelwood supply energy tomines, cattle introduced.Burning by settlers, miners’rush continues, golden age oftimber, fast rates of logging,sawmills, and railway.Public subsidy to plantationforestry, new roads, papermill industry, free tradeagreements signed,introduction of new intensivecrops.None.Shift from nomadic tosedentary communities withstronger links to the land andsocial organization.Protection of areas aroundvillages and water sources.First environmentalregulations, first public parks.Management of semi-naturalmatrix, paying forexternalities, need todiversify forest and crops,private conservation.Similar trends of forestrecovery at mid and highlatitudes worldwide.Slush and burn agriculture,spreading of weeds in NorthAmerica, Europe and Asia.Growing deforestation andsoil erosion globally. Goldrush in California andAustralia.Large-scale logging of forestsin New England and MidwestUS in late 1800s.Concentration of industrialactivity in cities. Firstnational parks.Conservation movements,private land protection,abandonment of farmland,forest recovery in Europe andNorth America. Consolidationof urban population,concentration of intensiveagriculture, use of fossil fuels.Fig. 10. Trends of increase in area of avocado plantations and vineyards at southcentralChile in the past two decades.that led to either loss or gain of vegetation cover. We used thechronosequence of events effecting Chilean forests to illustratethese transitions. The main drivers of these land cover changes andtheir consequences, as discussed in this paper, are summarized inTable 2. This analysis offers a broad framework for understandinglandscape change, which could be applied to other regions in Chile(Marquet et al., 1998; Nuñez and Grosjean, 2003). We offer commentsabout the application of this framework to Latin America andother regions of the world (Table 2).The first great transition, from about 18,000 to 11,500 cal. yr.BP, entailed the fast recovery of forests from small and sparseglacial refugia to the present extent of 13 million hectares in southernSouth America (Villagrán, 1991, 2001). This trend that wasnearly synchronous with paleoclimate changes recorded in theNorth Atlantic region and other southern hemisphere mid-latituderegions (Webb, 1981; Moreno et al., 2001). Human impact duringthis postglacial transition is globally perceived in the increased fireincidence, shown by charcoal remains in sediments from lakes insouth-central Chile and Patagonia (Markgraf and Anderson, 1994;Moreno, 2000; Heusser et al., 2000; Abarzúa and Moreno, 2008)and reconstructions of fire history from many sites in North America(Russell, 1997; Power et al., 2008). The dramatic decline of elmin northern Europe starting about 5400 to 4500 cal. yr. BP has beenattributed to the use of fire to open land for grazing (Williams,2008). In southern South America, the fire peak coincides with thewarmest and driest period of the entire Holocene (∼12,000 to 6000cal. yr. BP) representing the second major change in land cover sincethe postglacial recovery of mid-latitude forests. The last 5000 yearsof the Holocene are characterized by a gradual trend towards diversifyingcrops and significant land clearing, especially in the majorriver basins (Dillehay et al., 2008; Abarzúa, 2009). Trading of goods(e.g., fish, crops) among different ethnic groups provided access tonew foods and may have reduced the pressure on the land (Camus,2006). The worldwide process of land cover change largely associatedwith the clearing of land for farming seems to have beenslow at first, but it became accelerated in the past 2000 years,
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